The invention relates to an active chassis stabilization system including a hydraulic pressure supply unit, a hydraulic stabilizer assembly which is associated with a front axle, a hydraulic stabilizer assembly which is associated with a rear axle, and a control unit.
Generic active chassis stabilization systems are used by the majority of motor vehicle manufacturers in an increasing number of their models. Owing to the demand for increased comfort when travelling, an increased safety requirement and increasingly developed sensor arrangements, active chassis stabilization systems are becoming increasingly popular to support the passive components of the chassis. The passive components such as spring elements or dampers merely react to loads or forces which act on the vehicle. In active chassis, hydraulic or pneumatic actuators are usually installed, which are coupled with the passive components of the chassis. These actuators may be associated with an axle or else with the individual wheels of the vehicle. The vehicle data received by various sensors are converted by the vehicle electronics into actuating signals for the actuators. These then actively influence the behaviour of the chassis in accordance with the respective driving situation.
Such a chassis stabilization system in accordance with the current prior art is disclosed in WO 03/101768 A1. The chassis stabilization system described there associates a hydraulic actuator respectively with the front and the rear axle. The actuators are activated via an integrated control unit, the control unit representing the interface between the vehicle sensor arrangement and the hydraulic circuit of the chassis stabilization system. The integrated control unit is a compact component here, which receives both all the control valves of the hydraulic circuit and also the electronics for switching these valves.
In the currently known chassis stabilization systems, the possibility exists for switching the actuator/actuators of the front axle with the actuator/actuators of the rear axle in parallel or in cross-over, with the front and rear axles always being controlled with the same pressure.
The active chassis stabilization system counteracts rolling moments, i.e. moments about the longitudinal axis of the vehicle, e.g. as a result of travelling around a bend. In some embodiments, a pitching of the vehicle, i.e. a movement about the transverse axis of the vehicle, can be counteracted. Now it would be desirable to extend the degrees of regulating freedom of the active chassis stabilization system such that, for example, a control moment which counteracts a rolling moment is not imperatively divided in half between the front and rear axles. Owing to the usually stronger stress of the front axle, it would be suitable to also counteract this stress with a higher pressure than on the rear axle.
The use of two separate control circuits for the front axle and the rear axle would suggest itself. Apart from the economic aspect, namely the doubled effort for such a chassis stabilization system, the lack of available space also argues against such a solution. In addition, an integrated solution with a compact control unit, as shown in WO 03/101768 A1, would be unthinkable.